Star-tpc-l mailing list

[Richard Witt <witt AT usna.edu>]



Present: Alexei, Jim, Flemming, Tommy, Yuri, Gene, and myself

== Hardware

— some anode trips

— some problem with triggers

— currently running 6x6 bunches

— yesterday was good test for TPC 

— ~7 mbar jump due to front

— laser plot (drift velocity) dropped about 1% this morning

— suspicion of new gas quality?

— still watching, has not bottomed out yet

— no motion of TPC was observed during polarity flip last week

— some discussion with magnet experts

— maximum current ripple occurs on ramp-up

— trip goes straight through diode to zero, no ripple

— conclusion is magnet trips cannot be the cause of TPC movement

== Electronics

— ASIC Thresholds

— request from Tonko to increase TPX ASIC thresholds from 3 to 4

— intended to reduce data volume to facilitate speed increase

— originally set threshold at 3 during BES since there was no data volume limitation

— Yuri does not anticipate a problem with change to 4

— needs to redo dE/dx from scratch in any event due to new cluster finder

— some concern raised regarding impact of new threshold on low pt electrons

— thought is we will actually have better ID on electrons than before 

— will still require some work, Yuri is watching low pt electrons closely

— have better understanding of dE/dx than 5 years ago

— proposal to collect 2 million events with old threshold before changing to 4 (for comparison)

— group agrees with changing threshold to 4

— Tonko is also improving FPGA code

— progress slowed due to downtime for water leaks

— ran successful test on sector 1 only, easily 5 kHz

— currently around 2 kHz for TPX

== Software

— Gene reports that there are currently many error and warning messages in the log (from Tonko’s code)

— not urgent problem, just a note

— Tommy’s script is setup running automatic QA work

— Yuri checked calibration sample for 14.5 and 19 GeV Au+Au 

— looked at new dE/dx model

— ran 2 versions dev2 and SL23c, both are consistent

— no problem in 14.5 GeV, 2% shift in 19 GeV

— could just adjust by 2% and update calibration, could be done by Monday

— Yuri will send link to study plots

— few days to decide whether to keep as it is or update, by Monday

— Yuri still working on combined particle identification in O+O data (new dE/dx model)

— using information from TPC and ToF

— dE/dx needs new corrections for this, spline correction

== AOB

— nothing new this weeK

Best Regards,

  Richard

Sent from my iPad

-- 
"Education is the most powerful weapon which you can use to change
the world."

--Nelson Mandela

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 Richard Witt, Professor of Physics     Phone (USNA): 410-293-6675
    United States Naval Academy         Email: witt AT usna.edu
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